Crystalline 7-(2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetamido)-3-vinyl-3-cephem-4-carboxylic acid (syn isomer)

Abstract

The invention relates to crystalline 7-[2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetamido]-3-vinyl-3-cephem-4-carboxylic acid (syn isomer) useful as an antimicrobial agent.

What we claim is: 
     
       1. Crystalline 7-[2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetamido]-3-vinyl-3-cephem.-4-carboxylic acid (syn isomer) which shows the peaks at the diffraction angles shown in the following table in its powder X-ray diffraction pattern:   ______________________________________                                    
diffraction                                                               
angle(°)                                                           
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about 14.7                                                                
about 17.8                                                                
about 21.5                                                                
about 22.0                                                                
about 23.4                                                                
about 24.5                                                                
about 28.1                                                                
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       2. Crystalline 7-[2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetamido]-3-vinyl-3-cephem-4-carboxylic acid (syn isomer) which is obtainable by acidifying a solution containing 7-[2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetamido]-3-vinyl-3-cephem-4-carboxylic acid (syn isomer) at room temperature or under warming. 
     
     
       3. Crystalline substance of claim 2, wherein a solution containing 7-[2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetamido]-3-vinyl-3-cephem-4-carboxylic acid (syn isomer) is an aqueous solution of an alkali metal salt of said compound. 
     
     
       4. Crystalline substance of claim 3, wherein the acidifying of the solution is carried out at the temperature from room temperature to 40° C. at the pH from 1 to 4. 
     
     
       5. Crystalline 7-[2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetamido]-3-vinyl-3-cephem-4-carboxylic acid (syn isomer) which is obtainable by dissolving 7-[2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetamido]-3-vinyl-3-cephem-4-carboxylic acid (syn isomer) in an alcohol, continuing to stir the solution slowly under warming, then cooling the solution to room temperature and allowing the solution to stand.